In the past, there have been proposed techniques of creating a three-dimensional model of a desired space (see Document 1 [JP 1992-133184 A]). The techniques disclosed in Document 1 project lattice light to the desired space to thereby take a projection image, and determine positions and inclinations of fiat surfaces by use of positional relationships between lattice points of a lattice in the projection image.
The techniques disclosed in Document 1 classifies relationships between adjacent flat surfaces into bend, boundaries between steps, and boundaries within planes, and determines lines of intersection by determining boundaries between surfaces and determines structural lines of an indoor space, from the positions and inclinations of the flat surfaces. In summary, according to the configuration disclosed in Document 1, to extract structural lines of the indoor room including object already installed in the desired space, bend, boundaries between steps, and boundaries within planes are extracted.
Document 1 discloses that extraction of the structural lines in such a manner allows recovery of structural lines which cannot be detected from images due to being hidden by small obstacles.
By the way, in the case of replacement of cloth or installation of thermally insulating material in an indoor room, there may be need to perform measurement with objects installed in the indoor room being removed.
Document 1 discloses that the structural lines can be recovered stably even if regions are partially lacked due to presence of noise or small obstacles. However, the techniques disclosed in Document 1 are suitable for the three-dimensional model including structural components which are relatively large objects (for example, a desk), and therefore cannot generate a model of a three-dimensional object where objects installed in an indoor room are removed, for the purpose of replacement of cloth or installation of thermally insulating material.